(257n) Using Correlations to Enable Equation of State Calculations for Model Asphalt Systems

Authors: 
Masoori, M., University of Rhode Island
Greenfield, M. L., University of Rhode Island

Relationships between asphalt chemistry and macroscale properties have been estimated through an equation of state (EOS) applied to molecules selected via molecular simulations.  The group contribution method of Nannoolal et al. has been applied to all molecules in two model asphalts to determine critical properties and acentric factors of all molecules. These provide the required properties to use the common Peng-Robinson (PR) cubic EOS to predict phase behavior of multicomponent systems. The results for densities and thermal expansion have been compared to experimental results. Since cubic equations of state do not predict liquid density precisely, the COSTALD volume translation has been applied to improve density predictions. The results from PR EOS were further from experimental trends compared to results from molecular dynamics simulations.  However, EOS calculations take only a short time compared to molecular simulations and they provide a direct path to an approximate free energy. The results from PR without COSTALD volume translation for thermal expansion were closer to experimental trends than were the results from molecular dynamics.